On Thu, 2019-04-18 at 06:51:16 UTC, Michael Ellerman wrote: > From: Russell Currey <[email protected]> > > Without restoring the IAMR after idle, execution prevention on POWER9 > with Radix MMU is overwritten and the kernel can freely execute > userspace without faulting. > > This is necessary when returning from any stop state that modifies > user state, as well as hypervisor state. > > To test how this fails without this patch, load the lkdtm driver and > do the following: > > $ echo EXEC_USERSPACE > /sys/kernel/debug/provoke-crash/DIRECT > > which won't fault, then boot the kernel with powersave=off, where it > will fault. Applying this patch will fix this. > > Fixes: 3b10d0095a1e ("powerpc/mm/radix: Prevent kernel execution of user > space") > Cc: [email protected] # v4.10+ > Signed-off-by: Russell Currey <[email protected]> > Reviewed-by: Akshay Adiga <[email protected]> > Reviewed-by: Nicholas Piggin <[email protected]> > Signed-off-by: Michael Ellerman <[email protected]>
Series applied to powerpc next. https://git.kernel.org/powerpc/c/a3f3072db6cad40895c585dce65e36aa cheers
